Since Google way back when converted its generic user accounts into Google+ accounts, anyone using Gmail also has a Google+ account. (A small group of longtime Gmail account holders have ignored Google’s messaging and were never upgraded.) As of right now, you can’t sign up for Gmail without creating a Google+ account or vice versa.

If you are added to someone’s Google+ “circle” of contacts on the social network, that person will be able to send you a Gmail message by simply entering your name — regardless of whether you follow them on the service. Your email address is hidden until you respond to the message. Google says the change should make it easier for people to reach those they already know.

Google is automatically opting all Gmail customers into the system — but there is a way to opt yourself out. Here’s how to do it:

The Gmail change is rolling out over several couple days. You’ll get an email message like the one below from the Gmail team. The subject will be “Gmail Update: Reach more people you know.”

After you get this message, you’ll be able to opt out by going into your Gmail settings menu, which can be accessed by clicking on the sprocket icon in the upper right corner. Click the sprocket, then select “settings.” (The bottom of the email, in an area talking about how to control the change, includes a shortcut into settings.)

Once in the settings menu, you’ll want to scroll down a to a section called “Email via Google+.”

By default, Email via Google+ will be set to “Anyone on Google+.”

If you want to opt out of all this, change the setting to “No one.”

Once you’ve done that, don’t forget to scroll down to the bottom of this page and select “Save Changes.” If you don’t do this, you’ll remain on the default settings.